Effect of different feed rations on growth performance in various size classes of juvenile pikeperch, Sander lucioperca

The effect of different feed rations on RAS-based pikeperch juveniles' growth parameters was studied. Juvenile pikeperch were reared in three separate experiments (I, II, and III) at a temperature of 24 degrees C with initial body weights of the fish at 1.3, 9.4, and 25.6 g, respectively. Four applied feed rations increased by 0.5% in each experiment: 3.0, 3.5, 4.0, and 4.5% of body weight per day (BW day(-1)) in experiment I; 2.0, 2.5, 3.0, and 3.5% BW day(-1) in experiment II; 1.0, 1.5, 2.0, and 2.5% BW day(-1) in experiment III. Each experiment in triplicates lasted 28 days. The fish were reared in tanks with working volumes of 1.0 m(3) each. All experiments were performed in the same recirculating aquaculture system. The stocking density in experiments I, II, and III was 800, 400, and 200 individuals per tank, respectively. The results of experiment I showed the highest specific growth rate (SGR), weight gain (WG), and biomass gain at the feed ration of 4.5% BW day(-1) (P < 0.05). In experiment II, feed ration from 2.5 to 3.5% BW day(-1) showed the highest final weight (P < 0.05). In experimental III, feed ration of 2.0 and 2.5% BW day(-1) showed the highest final weight, SGR, and WG (P < 0.05). Only in experiment III, based on SGR and WG, second-order polynomial regression showed that the optimal feed ration for pikeperch was 2.35-2.39% BW day(-1).